1. Field of the Invention
This invention relates to a color solid-state imager.
2. Description of the Prior Art
Recently, the demand for television cameras which are small in size, light in weight and easy of use has risen with the spread of VTRs for industrial or domestic use. Therefore, a solid-state television camera employing a semiconductor integrated circuit (usually, IC or LSI) has attracted attention. In the solid-state television camera, a faceplate and an electron beam generating portion in a conventional image pickup tube are replaced with an IC body, which forms an independent solid-state imager. The solid-state television camera does not use any electron beam and is therefore superior to the image pickup tube in points of high stability, low power dissipation, convenient handling etc., and it is expected as a television camera in the coming generation.
The solid-state imager is formed in the shape of a layer, and consists of a semiconductor substrate portion and a color filter portion. Metal interconnections and insulating protective films are formed on the semiconductor substrate. Ordinarily, therefore, the surface of the semiconductor substrate is not flat but is uneven. According to the inventor's experiment, when a color filter was formed in such a way that a thin film of a photosensitive organic material was formed on a substrate having such an uneven surface and then exposed to light, the ultraviolet rays for the exposure were diffracted at the marginal edge of an exposure mask to lead to the surface of the substrate and were reflected by Al interconnections etc. to cause other parts than the mask to sense the light and to give rise to the so-called problem of "fogging". This resulted in the disadvantage that a pattern whose contour was clear and accurate was not formed.
An example in which a filter is formed directly on a semiconductor substrate having a photosensor portion is disclosed in "Technical Digest of International Electron Device Meeting", December 1976, p. 400.